The present invention relates to a piezoelectric/electrostrictive device. In more detail, the present invention relates to piezoelectric/electrostrictive devices made of piezoelectric/electrostrictive film which can be used for active devices such as various actuators or transducers, frequency region function components (filter), vibrators, resonators, and oscillators of transformers, and a discriminator, and sensor devices for various sensors such as an ultrasonic sensor, acceleration sensor, angular velocity sensor, impact sensor, and mass sensor, and the like.
In recent years, a piezoelectric/electrostrictive actuator has been used as an ink pump of a print head for use in an ink jet printer. For example, in Japanese Patent Application Laid-Open No. 6-40035 (hereinafter referred to as Patent Document 1), one example of an ink jet print head is disclosed in which the piezoelectric/electrostrictive actuator shown in FIGS. 9 and 10 is used.
An ink jet print head 140 is formed by integrally bonding an ink nozzle member 142 to a piezoelectric/electrostrictive actuator 145 made of a piezoelectric/electrostrictive film, and ink supplied to a cavity 146 formed in the piezoelectric/electrostrictive actuator 145 made of a piezoelectric/electrostrictive film is spouted through nozzle holes 154 disposed in the ink nozzle member 142.
In further detail, the piezoelectric/electrostrictive actuator 145 made of a piezoelectric/electrostrictive film is constituted of a substrate section 144 (ceramic substrate in Patent Document 1) and an operation section 178 (the piezoelectric/electrostrictive device in Patent Document 1) formed integrally with the substrate section 144. For the substrate section 144, a closure plate 166 and connecting plate 168 each having thin-walled flat plate shapes are integrally formed in a structure in which the plates are superposed upon each other via a spacer plate 170. In the connecting plate 168, first and second openings for communication 172 and 174 are formed in positions opposite to through holes 156 and orifice holes 158 formed in an orifice plate 150 of the ink nozzle member 142. The first opening for communication 172 has an inner diameter which is substantially the same as or slightly larger than that of the through hole 156. On the other hand, the second opening for communication 174 has a diameter which is larger than that of the orifice hole 158 by a predetermined dimension. A plurality of longitudinally rectangular windows 176 are formed in the spacer plate 170. Moreover, the spacer plate 170 is superposed upon the connecting plate 168 so that each one first opening for communication 172 and second opening for communication 174 disposed in the connecting plate 168 are opened with respect to each window 176. The closure plate 166 is superposed on the surface of the spacer plate 170 opposite to that on which the connecting plate 168 is superposed, and the openings of the windows 176 are covered with the closure plate 166. Accordingly, the cavities 146 connected to the outside through the first and second openings for communication 172 and 174 are formed in the substrate section 144.
For the piezoelectric/electrostrictive actuator 145 made of a piezoelectric/electrostrictive film, small pieces do not have to be bonded to one another piece by piece to form the operation section, a conventional problem related to the bonding is reduced or prevented, and superior operation characteristics can steadily be obtained. Moreover, the actuator can easily be prepared and can advantageously be formed to be compact.
In the piezoelectric/electrostrictive actuator 145 made of a piezoelectric/electrostrictive film structured and characterized in this manner, in recent years, in pursuit of enhancement of an image quality of the ink jet printer, there has been a demand for further miniaturization and higher integration of the piezoelectric/electrostrictive actuator. However, there have occurred problems that displacement is reduced and a necessary amount of droplets cannot be spouted.